Smart thinking delivers air cooler improvements

Paul Boughton

A solution developed to tackle all potential cooling problems. By Meindert de Boer and Femke Schaefer

The area of De Botlek, part of the New Meuse development in the Netherlands, is characterised primarily by the petrochemical industry, tank storage companies and the storage of dry bulk goods to a lesser degree.

According to the Dictionary of the Dutch Language, the name Botlek refers to a 'leak' (Dutch: lek) in the sea channel of the river Meuse, where in days gone by fishermen used to catch bot (flounder) in large quantities. The flounder have since moved away and, in their place, industry is now flourishing in the area. In 1956, the first company, Dow Chemical, set up business in De Botlek, soon to be followed by other companies until – by 1960 – all the available land had been allocated.

Customer requirements

LyondellBasell was one of those early companies. Its systems – including air coolers – have been in operation since 1970. The engineering agency Jacobs recently commissioned Bronswerk to improve the capacity of two bays of LyondellBasell’s induced draft air cooler.

An improvement like this is not without challenges, however, since the improved system needs to comply with the latest specifications and requirements. In this case, for example, LyondellBasell specified the following additional, new requirements to be taken into account:

* 10% more cooling capacity; because of required additional cooling capacity 

On top of that, 15% extra cooling capacity, if this was possible, but with the lowest possible noise emissions – preferably under 74dB(A); because of noise restrictions and environmental concerns

* Any extra motor capacity required had to be within the limits of the existing cables, which were not being replaced (30KW) 

Due to the corrosive environment, the material requirement for the housing was stainless steel standard RVS 316L

Finally, all of the above tasks were to be carried out within the shortest possible delivery time

Possible solutions

Bronswerk rose to the challenge, its first task being to realise 10% extra cooling capacity. In addition, it needed to realise yet another 15% extra overcapacity while still sticking to the current dimensions. Increasing the bundles was not an option as they needed to comply with the existing dimensions. So the only possible way of increasing the cooling capacity was to press more air through the bundles. The disadvantage of this solution, however, was that it required high engine capacity and that the ventilators produced noise emissions that were too high (LyondellBasell’s list of requirements clearly stated that the noise emissions and motor capacity were to be kept as low as possible.)

Given that extra air had to be pressed through the bundles, the next step would obviously have to be to examine alternatives for the ventilators. There were two possible options. The first was that with conventional ventilators, 10% extra cooling capacity could be created, but noise emissions would be 8dB(A) (too high) and the motor capacity 45kW (too high for the existing cables).

The second option was that, given that conventional ventilators would exceed the noise requirements, Bronswerk considered using the SX ventilators from Howden. They too could be used to create 10% extra cooling capacity, but then with noise emissions of 75dB(A) (a little too high) and a motor capacity of 55kW (much too high for the existing cables).

Both scenarios could create the 10% extra cooling capacity but neither could deliver the required extra overcapacity and, moreover, noise emissions and motor capacity would be in excess of what had been specified. Bronswerk then decided to consider its own Whizz-Wheel cooling system, which it had developed for exactly these types of conditions. In concrete terms, the solution was Option 3. The idea was that with the Whizz-Wheel cooling system, 10% extra cooling capacity could be created, and, on top of that, another 5% of overcapacity (admittedly not the 15% requested by the customer). This solution would result in noise emissions of just 70dB(A) instead of the maximum of 74dB(A) set by the customer, and a corresponding motor capacity of just 22kW, which is well within the cable tolerances. 

With Option 3, Bronswerk was able to satisfy almost all the customer’s wishes and requirements. Realising the desired 15% overcapacity would be possible too, but only at the expense of compromised low motor capacity and low noise emissions. The customer was delighted with the very low noise emissions and low motor capacity and subsequently lowered the requirement of 15% overcapacity to 5%. Moreover, it proved possible to complete the assignment in a very short time. The order was received in October 2014 and completed in March 2015.

For more information at

Meindert de Boer and Femke Schaefer are with Bronswerk

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